Discussion in 'The Watering Hole' started by Winston, Jul 9, 2018.
Very interesting and thorough.
Not bad, but missing some details. Sure, magnetic exploders were junk in those days, but the real details of the impact det was not explained. When they hit at 90 degrees straight on angle, the firing pin, which was sideways, experiences great friction and did not put enough force on the primer. Off angle hits would usually work.
The internal failures of the contact mechanism can best be understood through the forces at work in a live torpedo. When a 3,000-pound torpedo traveling at 46 knots struck the hull of a ship, incredible forces were unleashed. The initial force of deceleration equaled approximately 500 times the force of gravity. Transferred to the firing pin, this force appeared as friction between the pin and the guides along which it traveled for accuracy. These stud guides were exposed to nearly 190 pounds of pressure from the contact and resulting deceleration. The firing spring was unable to overcome this tremendous friction and pressure with enough force to drive the firing pin successfully into the primer caps. When a torpedo struck a glancing, angled blow, the force of impact was lessened enough to allow the spring to push the pin into the caps, causing detonation.
The solution turned out to be relatively simple. The Pearl Harbor workshops designed and mass-produced modified firing pins from the propeller blades of Japanese aircraft downed in the December 7, 1941, attack. The new pins were made as light as possible in order to reduce the friction on the stud guides. Testing this handiwork, Lockwood ordered the submarine Halibut, armed with modified exploders, to repeat the Kahoolawe tests. Each torpedo was again set to run as close to 90-degrees as possible to fully test the new pins. Six out of seven torpedoes exploded. Although one still failed, it was a significant improvement from a 70 percent failure rate.
During the 1930s, the Bureau of Ordnance had conducted similar tests designed to ensure a reliable contact mechanism in time of war. The Newport Torpedo Station flung torpedoes against steel plates over sand and discovered then that the firing pins failed to strike the caps with sufficient force. Their solution was to increase the strength of the firing spring. The tighter spring seemed to solve the problem, but it did so at the speed of 1930s torpedoes. Torpedo speeds had increased to 46 knots by World War II, and this increase created greater impact forces. The increased speed essentially negated the strengthened spring. If Tinosa‘s torpedoes had been set for slower speeds or obtuse angles, Tonan Maru No. 3 would not have escaped. It took almost two years of wartime trials and tribulations, but American submariners were finally equipped with reliable and effective torpedoes.
NOT MENTIONED IN THE VIDEO is that 2 US subs were sank in WW2 by their own circling torpedoes. I think if they would have dove deep after firing, they would have survived. Note that all modern US units have an extra gyro whose only job is to prevent firing in this event.
ALSO, they did not mention the cool Japanese Long Lance, the best one of WW2. Bigger, faster, longer range, and bigger warhead. And used PURE oxygen for oxidizer, a real problem as it took 2 days to purge all the oil out of the plumbing before fueling. As anyone with a cutting torch knows, the smallest amount of oil in your O2 lines will create a BOOM.
Our modern torps use a swashplate engine. Weird. Pistons thru a linkage make a plate wobble, which translates to rotation. Very powerful maybe 500-900 HP. Uses OTTO fuel which is like liquid TNT, has all you need to burn, the gas is distributed to each cylinder, and a rotary valve routes the exhaust thru a hollow propeller drive shaft exhaust. When they scaled up the first prototype, it exploded and almost killed people. Nice story: A test of the MK48 was being viewed by an overhead chopper. The rotor blades created ripples on the water, which the torp seeker responded to. It headed up, flew out of the water, and almost downed the chopper! True story, I worked at the Westinghouse plant, but on other stuff.
Here is my fave, the ASROC. Rocket powered, nuke warhead. LET'S ROCK!
Winston really posted a great video, those not really interested in torpedoes, but the history of technology should watch it, worth 46 min. I really liked the FLYWHEEL POWERED TORP, spun up to 10,000 rpm. Cool thing is that they wanted constant speed, as wheel spun down, would slow, SO...they made a variable pitch propeller, with mechanism that would alter pitch to keep speed constant. Remember this was with 1910 tech, just gears, cams, levers, springs, etc. Intricate mechanisms.
ALSO, the early torps in the US were great examples of STEAM PUNK
(a cult art following of old tech, google it, and look at pictures).
Mostly machined out of brass, LOTS of wild complex gizmos, almost hard to believe. They needed electronics, servos and cnc production, but instead were all hand made and custom, ignored Ely Whitney (interchangable parts).
Let's not forget the impressive 229 MPH Va-111 ROCKET/NUKE TORP from Russia. Out on the edges again. Bravo.
I worked at Huges Aircraft on the signal processor in the ADCAP Mark-48. The capabilities of that thing (40 years ago) were scary. 'Wake Homing": If it's upward-looking sonar detects it has crossed the wake of a ship, it will turn and follow the wake, and go boom.
Interesting, how many firms worked on that torp? Gould, Westinghouse, Alliant Tech Systems, now Hughes! I always thought that trailing wire control thing was odd, if the subs can communicate with the VLF radio underwater, why not talk to the torps that way? So the seeker does look up, it thought the heli waves on the surface was a wake. This is probably something we should not be talking about..
The Confederate sub Hunley was the first to sink a ship, with a spar charge, a hook rammed into the wood would hold the charge, then they backed off. I was wondering how they could light the fuse underwater, doh, so looked into it. Turns out they used a flintlock thing or rifle cartridge with firing pin, if available at the time, to set it off, with a really long string. But even a 1000' string might not be enough. They did not understand back then how well sound and pressure disturbances traveled thru water. The blast effects sunk the sub.
I can rant about torp sonars, sat next to the guy who designed them. Funny piezo discs like lifesavers candy, high voltage drive, one system was about 14KW, they said it would kill a frogman in front of it.
VLF is not only very low, it's VERY slow (35 bits per second), and very energy intensive. You likely couldn't transmit enough data to control the torpedo, and doing so would reveal the sub's position.
Ah, I see. I find it odd that any radio wave can travel under water.
Some day they will get a blue laser beam shot from a satellite that will go thru the water and find subs, they will all be mothballed. Only 2 legs of the triad left. It might fall over.
If anyone is old enough to have seen VOYAGE TO THE BOTTOM OF THE SEA tv show in the 1960's, note that no one has made a flying sub yet, looked like a manta fish. Pretty cool. Skunkworks could do it.
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